What fluid for custom system?

[matt2491]

I'm putting together a hydraulic system that uses a GM automotive power steering pump to run industrial valves and actuators (one rotator and one cylinder). I've been trying to figure the best fluid to run that will be compatible with all components in this system. Will standard hydraulic fluid upset the automotive p/s pump? Can I run ATF? What would be my best bet?

This is like debating motor oils... but with even more confusion.

 

[hydtools]

You could use ATF. I would choose a high VI ISO32 hydraulic fluid. ATF will hold moisture and should be run fairly hot to drive out the moisture. Trannies run upwards of 180F, hydraulic systems should be run no higher than 140-150F.
Ted

 

[matt2491]

Cool, thanks for the response. Someone else recommended John Deere Hy-Gard and/or other similar 'high end' hydraulic fluid. Do you think that would be a good option?

 

[hydtools]

Sure, you could use it. It has a high VI of 190, good for wide temperature use range. It has performance enhancing additives, e.g. anti foaming, extreme pressure/anti wear. But it has additives to retain more moisture, which may be ok, and to improve wet clutch and wet brake functions. Friction modifiers not necessary for your application.
I'd prefer a fluid not specifically formulated for transmissions and brakes.

Ted

 

[romke]

automotive power steering pumps are usually run on ATF because that fluid is readily available worldwide, not because it is the most suitable fluid.

i see no reason why a quality industrial hydraulic fluid cannot be used - for use in hydraulics a good industrial hydraulic fluid might well be superior to a atf as long as you keep it moisture free.

a tractor transmission fluid is also a alternative, however that also is a kind of multifunctional fluid which usually results in less then optimal performance as hydraulic fluid.

the use of tractor fluids and atf in pure hydraulic systems is based on the fact that they always met known and worldwide used standards, whereas the quality of pure hydraulic fluids did not always meet known standards and where not available everywhere. that situation has changed and now hydraulic fluids meeting internationally known and accepted standards are readily available anywhere.